Antimicrobial peptides may be found in nature and may also be found in synthetic peptides. These antimicrobial peptides consist of relatively short amino acid sequences (10 to 100 amino acid residues) compared to normal proteins. When these antimicrobial peptides mostly bind to the cell membrane, 1) they form ion channels on the cell membrane and thereby inhibit the energy production of the microorganism, or 2) generate large holes in the cell membrane, resulting in the death of the cell. Since these antimicrobial peptides physically destroy microorganisms, it is very difficult for microorganisms to have resistance to these antimicrobial peptides unlike conventional antibiotics that inhibit the synthesis of microbial cell walls or intracellular polymers, and thus no resistance to these antimicrobial peptides has been reported until now. Although there is little sequence similarity between many antimicrobial peptides known to date, there appear to be some general tendencies with regard to their structures and activities. Representatively, antimicrobial peptides have a positively-charged moiety, such as lysine, arginine, and histidine, and a hydrophobic moiety. Currently, in the Shai-Matsuzaki-Huang (SMH) model, which appears to be most persuasive among the hypotheses suggested being related to the action mechanism of antimicrobial peptides, the characteristics of sequences and the mechanisms of antimicrobial peptides are described as follows: after the positively-charged hydrophilic moiety binds to the negatively-charged cell membrane of bacteria, the hydrophobic moiety of the peptide bound to the cell membrane interacts with the hydrophobic moiety of the phospholipid of the cell membrane and forms pores on the cell membrane to change the permeability of the cell membrane, thereby destroying the cells. Formyl peptide receptor group (formyl peptide receptor 1 (FPR1) and formyl peptide receptor 2 (FPR2)) expressed in phagocytic cells, such as neutrophils and monocytes, plays an important role in host defense against pathogen infection (Mangmool, S. et al., Toxins, 3: 884-899, 2011). These receptors are known to bind to the pertussis toxin-sensitive Gi protein (Nakashima, K. et al., J. Biol. Chem., 290(22): 13678-91, 2015). Between the receptors, FPR2 is known to play an important role in inflammatory diseases. Activation of FPR2 induces the separation of the Gβγ subunit from the Gαi subunit and the βγ-subunit induces the activation of phospholipase Cβ or phosphoinositide 3-kinase (Duru, E. A. et al., J. Surg. Res., 195(2): 396-405, 2015). Activation of these molecules induces complex downstream signaling thereby modulating in vivo immune responses by diversifying cellular responses such as chemotactic migration, degranulation, and superoxide generation.